Electrical connectors for use underwater are known, for example from United Kingdom patent application No. GB-A-2,192,316, to have first and second connector parts in which the first connector part has at least one pin projecting from a support which is inserted into a housing and fixed in place by a retainer ring. The pin has an axially extending conductive copper core surrounded by an insulating sleeve which is arranged to expose an area of the conductive core at or near the tip of the pin for making electrical contact with a contact socket in the second connector part.
The housing extends in a forward axial direction from the support, radially outwardly of the contact pin, for alignment with and to receive a housing of the second connector part during interengagment. This extended housing of the first connector part defines a pin chamber in which the pin extends.
In the de-mated condition this pin chamber is exposed to the external environment and flooded with, for example, sea water. The conductive core at the tip of the pin is then exposed to the external environment, as is the insulating sleeve and the front face of the support.
The second connector part has a seal around an opening for receiving the pin in sealed manner when the first and second parts are inter-engaged, or mated. In the mated condition a portion of the pin near the support remains exposed to the external environment, such as sea water.
Electrical connectors of this type are known as wet mate connectors, because they are capable of being mated when underwater.
Wet mate connectors are used in the oil and gas industry to provide electrical power to electrical submersible pumps (ESPs) or compressors. ESPs are located in subsea wells and require electrical connection though a subsea well head. The ESP has an electric motor supplied by a cable connecting the motor to a wet mate connector at the well head. The cable may be connected to the back end of a first connector part as described above. A second connector part for mating with the first connector part pin is connected at its back end to a cable which is supplied from a remote power source, for example at the surface. The environment in which the first and second connector parts are used is subject to high temperatures, for example as high as 200° C. The environment is also a high pressure one and moreover there may be significant pressure differentials between the back of the support of the first connector part from which the connector pin projects and the pin chamber where the pin projects forwardly from the support. There is a challenge to design connector parts able to handle the high temperatures, high pressures, pressure differentials, and also capable of supplying sufficient power to meet the needs of the downhole equipment.